Automated apparatus for eviscerating large bodied fish have been available for some time. One example of such apparatus is disclosed in U.S. Pat. No. 5,554,069, "Apparatus and Method for Subdividing a Fish into Loin-Containing Portion and Viscera-Containing Portion" to Burch et al. The apparatus disclosed therein comprises a conveyor upon which a large-bodied fish, such as a tuna fish, is carried with its belly portion pointing upwardly. Two rotating blades arranged in a "V" configuration slice through the belly portion of the fish in a pair of angled, intersecting cuts to substantially remove the viscera-containing portion of the fish from the loin-containing portion. This apparatus is not suitable for processing smaller bodied fish or batch processing fish having different sizes.
Smaller fish, such as pollock, while comprising a substantial portion of the total quantity of ocean fish caught have traditionally been considered a waste product and are often thrown back into the ocean. The recent decline in fish populations have rendered smaller fish, such a pollock, more valuable. However, satisfactory apparatus and methods are currently unavailable for processing pollock and other small fish in a cost-effective manner. U.S. Pat. No. 3,804,964 to Hogstedt et al. entitled "Method and Apparatus for Treating Fish" describes a method for processing small fish incorporating steps of soaking and agitating pre-cut fish portions in large vats of water from between 15 to 120 minutes, with an optimum time of about 60 minutes, to separate the fish protein from viscera and other undesirable portions of the fish. Such a process, however, is not commercially acceptable for the production of high quality minced fish muscle products and surimi and is therefore not a viable process for processing pollock and other small bodied fish.
Beginning Jan. 1, 1998 the North Pacific Fisheries Management Council (hereinafter "NPFMC" ) required that all harvested pollock be retained and utilized. This is a problem in the pollock fishery where small fish are often unavoidable and represent over 25% of landed weight in some situations. Additionally, in all world fisheries small fish and flatfish are often not used for human consumption due to low yield, high labor costs, and high equipment costs. The term "small fish" as used herein means fish that are 15 cm to 40 cm in length (6 inches to 16 inches) and weigh from 80 grams to 500 grams (0.18 lb. to 1.10 lb.).
There are currently five options to retain and utilize small pollock and other fish species. These five options are described below along with their economic limitations.
1) Fishmeal--Putting whole fish in the meal process undesirably takes capacity away from processing offal and complicates raw material handling for processors. If the fish meal plant capacity is maximized due to small fish, the processor must limit production of more valuable primary food products and lose potential revenue during limited fishing periods. If the fish have been bought from a catcher boat, then loss is estimated to occur if the cost of pay fish sent to meal exceeds 2.5 cents per pound. This is based on seven metric tons of fish to produce one metric ton of meal and a production and handling cost of $100.00 per ton of finished meal. Calculating using the above information gives a cost of meal as $485.00/metric ton. Finally, recovery of muscle food products from whole fish have a much higher value than fish meal. PA1 2) Conventional filleting machines--Toyo Sulsan Kikai Co., Ltd., Osaka, Japan, and others manufacture filleting machines which are used almost exclusively for processing pollock. The economic limitations for small fish processed with these machines are yield, speed, labor, machine cost, equipment space, and quality. Each of these factors are discussed below. PA1 3) Low grade products--The third option for retention and utilization of small fish is production of minces, headed and gutted fish, or whole frozen fish. These products satisfy the retention and utilization requirements but produce low value products that compete with production and storage resources that are needed for higher profit producing products. This approach is a step towards utilization of the fish resource but still does not solve the problem of good economic use of small fish. PA1 4) Small fish filleting machines--The fourth option is using small fish filleting machines. Adapting herring or pilchard filleting machines is a possibility. The option that is being pursued by some processors is the use of the Toyo 167 model that is made specifically for small pollock. The cost for this machine is $110,000.00 excluding installation, conveying equipment, and plant modification to integrate this machine. Two skilled operators are required to reach an average target speed of 180 fish to 200 fish per minute. This option solves the efficiency problems of processing small fish in conventional filleting machines, but still has the overhead of high cost, space limitations, inflexibility, and speed. PA1 5) At sea dumping--In unregulated fisheries many tons of small fish and flatfish are dumped back in the ocean as waste. This is due to lack of an economic process to handle these fish. It is well documented that shrimp trawlers catch five to ten times more fish than shrimp. The by-catch from shrimp trawling is then dumped at sea. Obviously, this option is economically and ecologically unsound.
Yield--These machines, in general, were not designed to process small fish in the six to sixteen inch range. Small fish do not align properly in the machine, if at all, and the cutting blades remove too much meat from smaller fish. This results in muscle recovery, as percentage of round fish weight, that is significantly lower than larger fish for which the machines were designed.
Speed--The Toyo filleting machines can run up to 280 fish per minute. Very good performance over a twelve hour shift for these machines would be an average of 210 fish per minute. These speeds would be very difficult for top operators to achieve when working with small fish. The reduced speed combined with poor yields place an economic burden on producers in addition to wasting a food resource.
Labor--Two or three operators are needed to operate each filleting machine. This is a significant cost for operating a machine that is inefficiently cutting fish for which it was not designed.
Machine cost--The cost to install one complete filleting machine line is in the $250,000.00 to $500,000.00 range. Parts and labor to maintain these specialized machines also make performance and output extremely important.
Equipment space--Conventional filleting equipment and lines require valuable production space for equipment, operators, material feed conveyors, and waste handling. Additionally, this equipment is permanent and cannot be moved without a major overhaul of the processing facility and processing lines. These space costs and inflexibility become increasingly important when the fish size is below where conventional equipment can operate efficiently.
Quality--As stated above, conventional Toyo and other machines were not designed to handle fish in the six to sixteen inch range. The first problem occurs at the head cut. For some filleting machines there is a measuring and pushing device to maximize the position of the head cut near the gill plate. This system is operating below machine design and is marginally effective depending on the skill of the operator and the talent of the staff service mechanic. The Toyo filleting machines have rotary brushes that push fish forward to a head bar before the heads are cut off. Smaller fish headed in a Toyo machine seldom have the cut near the gill plate to maximize quality and recovery. The fish are often nearly cut in half with the high volume and quality dorsal and nape meat severed with the head. The next problem is the "grip" belts that convey headed fish through the splitting and filleting section of the fillet machines. Small fish do not align properly and are not held tightly enough to maximize the precision cutting of the filleting and boning knives. There is also a high dropout rate where small fish fall out of the "grip" belts and into the offal stream resulting in reduced recovery. Small improperly headed fish tend to roll when dropping into the "grip" belts from the fillet machine heading section. Fish that are not aligned with the bellies straight down are much less likely to be completely eviscerated and have the body cavity brushed and rinsed. The result is fish fillets with varying amounts of attached viscera and black belly cavity membrane. Minced meat quality produced from these fillets is lowered by proteolytic enzymes and bacteria from viscera. Black belly membrane lowers minced meat quality with visible "black spot" impurity in the white minced flesh. Low quality minced meat reduces recovery and grade quality in the surimi process.
Thus, there is a need for a process that can economically recover fish muscle for human consumption from smaller sized fish. Requirements are high speed to produce sufficient volume of material from small fish, low capital cost and maintenance, low labor and operating cost, and high yield.